Final answer:
Xylem in plants is made up of parenchyma cells, tracheids, and vessel elements.
Step-by-step explanation:
The cells that make up xylem in plants are parenchyma cells, tracheids, and vessel elements.
Tracheids are xylem cells with thick secondary walls that are lignified. They allow water to move from one tracheid to another through pits on their side walls.
Vessel elements are shorter and have thinner walls compared to tracheids. They are connected to each other by perforation plates on their end walls, allowing water to move through them.
Xylem parenchyma cells are also present in xylem tissue, but they do not conduct water like tracheids and vessel elements.